1. Field of the Invention
The present invention relates to mold clamp fixtures and more specifically to a mold fixture used to clamp together male/female mold assemblies in the production of contact lenses.
2. Description of the Prior Art
Contact lenses are produced using lens molds. The lens molds typically have a male and female portion which mate together to form a cavity in the shape of the desired lens. Prior to mating the male and female lens molds together, the female mold is filled with a liquid lens material. The male mold is then placed over the female mold and the lens material is squeezed into the desired lens shape. The liquid lens material is then hardened into a lens by the introduction of ultraviolet light into the mold cavity. The ultraviolet light impinges the outside of the mold and passes into the internal cavity due to the transparent properties of the mold material.
The male and female lens molds are clamped together within a pair of mold clamp fixtures. The female lens molds are placed within cavities in a first fixture. The male lens molds are placed within cavities in a second fixture. The fixtures support and align the mating lens molds. When the two fixtures are mated, the male and female lens molds are clamped together in the proper alignment. Each fixture has multiple cavities to accept the male and female lens molds, and hence multiple lenses are produced within the fixtures during each clamping cycle. The number of cavities within each fixture is limited by the physical size of the lens molds and the structural considerations of the fixture. The fixture cavities may be positioned adjacent to one another within the fixture body with the limitation that the lens molds must not interfere with one another during the molding cycle.
During the molding cycle, the mold clamp fixtures must also provide a controlled clamping load to the male and female molds. A sealing lip is used about the periphery of the lens mold to provide a liquid seal when the two molds are clamped together. The fixtures must apply a clamping force to the lens molds in the area of the sealing lip without any appreciable deflection of the assembly. Any deflections of the clamp fixtures may result in deflections in the lens molds and result in imperfections in the finished contact lenses.
Therefore, there is a need for a mold clam fixture accommodating a greater number of contact lens molds within a given size fixture.